Machine tool carriage reciprocating mechanism



Sep- 3, 1957 G. E. coMsT'ocK ab 2,804,735

MACHINE TOOL CARRIAGE RECIPROCATING MECHNISM Filed Nov. 28, 1955 lNvENToR 77 5517/2156 E. zmsraak 3M TTOENE Y nited States Patent M MACHINE TOOL CARRIAGE RECIPROCATING MECHANISM George E. Comstock 3d, Princeton, Mass., assignor to Norton Company, Worcester, Mass., a corporation of Massachusetts Application November 28, 1955, Serial No. 549,397

4 Claims. (Cl. 51-233) The invention relates to machine tool carriage reciprocating mechanisms.

One object of the invention is to provide reciprocating mechanism which will enable machine tool carriages to be driven at far higher speeds than are now customary, such as speeds up to double or even quadruple present speeds without at the same time setting up, by the reacting 4forces at reversals, such vibration in the base of the machine tool as will impair its ability to generate geometrically true surfaces. Another object of the invention is to provide such a mechanism which is simple and will not easily become deranged. Another object is to provide a mechanism of the type indicated which requires little or no maintenance.

Other objects will be in part obvious or in part pointed out hereinafter.

In the accompanying drawings schematically illustrating one of many possible embodiments of the invention,

Figure l is a front elevation of a machine tool mechanism of the invention with the front wall of the machine broken away in many places the better to illustrate the mechanism,

Figure 2 is a vertical sectional view taken on the line 2-2 of Figure l,

Figure 3 is a vertical sectional view showing a modification of part of the mechanism,

Figure 4 is a view mostly in vertical section showing a modification of another part of the mechanism,

Figure 5 is a detailed View showing a portion of the relief Valve in section.

Referring now to Figure 2, the base of the machine tool, which in many cases will be a Vgrinding machine, has ways 11 and 12 supporting a carriage 13 having complementary surfaces and 16 nicely fitting the ways 11 and 12 thus to mount the carriage 13 for reciprocation. Referring now to Figure 1, as well as Figure 2, secured to the under side of the carriage 13 are brackets 17 and 18 connected to piston rods 21 and 22 connected to pistons 23 and 24 in an internal cylinder 25 formed in the upper part 26 of a large mass 30 which may conveniently be a piece lof cast iron. Referring to Figure 2, the large mass 30 has way surfaces 31 and 32 resting on ways 33 and 34 formed on the upper surface of a horizontal web 35 also well shown in Figure l. The mass 30 is thereby also mounted for reciprocation and in a direction parallel to the reciprocation of the carriage 13.

As shown in the left hand side of Figure l, there is a long slot 37 through the web 35 through which downwardly extends a bracket 39 which is secured to the under side of the mass 30 and it is connected to a piston rod 40 connected to a piston 41 in a cylinder 42.

Referring to both igures, extending through a bore in the mass 30 is a long rod 45 the ends of which extend into the end walls of the base 10 and which shaft 45 is secured to the left hand end wall, for example as by means of a set screw 46. Referring to Figure l, on the shaft 45 and extending between the left hand end wall of the base 10 and the mass 30 is a spring 47 while on the shaft 45 and $4,735 lce vlatented Sept 3 1957 extending between the right hand end wall of the base 10 and the mass 30 is a spring 48. To make room for long springs, the mass 30 can have counterbores 51 and 52 as shown. However, in some cases the springs 47 and 48 or other equivalent means may be between some stationary abutments and the mass 30, and may become active only when the mass 30 has moved some given distance. This is illustrated in Figure 3.

The carriage 13 is reciprocated by any desired hydraulic or pneumatic reciprocating mechanism of which so many are known in the art and have been described in patents and in the literature and are in daily use that I deem it unnecessary to describe any particular one herein. Reversals .of direction of reciprocation are customarily made by means of carriage dogs 53 and 54 in a T-slot 55 striking an interposed reversing lever, not shown, which reversing lever actuates a valve to change the flow of hydraulic or pneumatic fluid. Illustratively I show pipes 57 and 58 connected to ports 59 and 60 admitting and vexhausting iluid from the left hand and rig-ht hand ends respectively of the internal cylinder 25.

If high carriage speed is attempted in the usual grinding machine the shock of reversal vibrates the whole machine so that beyond some certain speed for each machine poor results will be achieved with respect to surface finish of the workpiece or the like. Yet for a long time higher carriage speeds have been Wanted for such machines as cylindrical grinders and surface grinders. In accordance with this invention higher carriage speeds may be achieved without setting up detrimental vibrations because the large mass 30 connected as it is to the cylinder element of the piston and cylinder apparatus (or the arrangement might be reversed and the mass might be connected to the piston element with the cylinder element connected to the carriage) absorbs the momentum of reversal by itself moving but, according to the laws Vof physics, for a limited distance only. The reason for the springs 47 and 48 now becomes apparent in that they tend to center the large mass 30 to keep it from drifting too far from the median location shown. Figure 4 illustrates the reversal of the arrangement shown in Figure l, in that in Figure 4, the upper part 26 of the cylinder 25 is connected to the carriage 13and the piston rods`21 and 22 are connected bythe brackets 17 and 18 to the large mass 30.

The piston 41 in the cylinder 42 acts as a dampener to the reaction induced reciprocations of the mass 30. I show a port 61 in the left hand side of the cylinder 42 and a port 62 in the right hand side of the cylinder 42. The port 61 is connected by piping 65 to a throttle valve 70 which is connected to a T-union 71 connected to the port 62 and to a relief valve 75 which in turn is connected to the main pump 77 which is connected to intake piping 78 extending into a sump 80 formed in the base 10. The relief Valve exhausts through piping 81 into the sump 80. This assumes that in the illustrative embodiment the fluid is hydraulic and in the usual case this will be oil and in most applications of the invention the machine will probably have hydraulic reciprocating and controlling mechanism. At least such is the preferred form of the invention to the best of my present knowledge. This same pump 77 can operate the pistons 23 and 24 and a pipe 82 is shown leading the fluid to the hydraulic controlling mechanism that is not shown. A return pipe 85 from such hydraulic operating mechanism is shown in Figure l which returns the fluid such as oil to the sump S0. As the dampener cylinder 42 should not be connected to exhaust uid through the relief valve 75 in the best embodiments of this invention, the relief valve 75 contains, as shown in Figure 5, a check valve '76 associated with the port leading to the T-union 71 which check valve 7 6 allows iiuid to go to the dampening cylinder from the pump i7 3 but not to exhaust from the dampening cylinder into the sump 80 through the relief valve 75.

By manipulating the valve 'Z0 opening its wide or closing it a bit, the dampening effect can be varied at will. At the bottom right-hand s'idejof figure Irsho'vv V'valve wheelv 90-'to Acontrohthe valve Y10' by turning a valve 'shaft 91 which i's connected'to the movable valveA element. r1` It'will-beseerr that-if'the'largeimass 30T'takes'up an average"positiontodhe leftY of themedian position? the springy 47Will'eXert' force to' return 'itto Ysuch medianpositioiand' if on Ithefotherhand 'the'large mass Sassumesia position somewhat to the right of thev hiedianfpositi'on, thespring 48Will exert v'a forcertoreturn it" tosnch median position; "Sprin'gs from"theirverymature exert'more forcethe more-ahw' are 'compressedmn' therefore' the greater the" deflection `the`e great'erfthe forc' tending i" to caise thel massto reassiime its'fmedianposition @There is, however, plentypfroomfor detletionsof 'the mass 30 totle left Aand? to th right and'fo'f course more'oless' roomffor 'deilection"cnbe provideda'ssdesi'red'.' f f 4`vWth'lth'monient'm 4'of reversals of the"carriage 13 abSorb'edhby idle'reciprocation' ofthe large: massBl much hg'h'erspeeclsA` can be .gveftothe carri/age 13 lthan 'hereto--l foreipra'ctical' withouticausing 'undue""vibration" For obtaining large speeds in the tir'st vplace it issuiicient4 'to provid'f'mo're' "po'v'verfur"pumps motors and" larger pipes?"The"-l'mrrip"-"7'1"V is shown as driven'by a`n`ioto'r '95 through afreduction gearing" 961 The""reaso'n 'for rcoriL meeting*l the circuitof the cylinder 42 to tliepump' 7'1" is simply to"keep the dampening circuit includin'gthe c'ylin der242 always'full of oilto compensate for le'aksj and' if agood tight system full'ofoil-can be provided this feature can'f'be eliminated? Infinanycasesithe dampening meansto dampen the resulting"reciprocations v'of the large mass 'due tov the' reactioni from f'revers'al- Ao'f Vthe lcarriz'ig embodied herein in' the-'piston "41, cylider"42` land' pipe' connections'shwn may be dispensedffvvithf-"This will r'esiilt, however', "in" greatei" amplitde'omovement of the mass '3'0 vs'o :there isfa'advantage in skingsuchidamp'enih'g means? In soin'e cases 'the vsprings g47I;a"n`d 48 or ieqnivalentmeans exerting opposed* forceso'n I the`l ilarge E mass 'vvli :are: increased When" the mass' ismoi/"edV aginst'thef l vmight be omitted relying' on the' prop" it i n, that'iaisl theireatioi'is at reversal are'ec'lualinnerg'y; thena's's' will lEend "to reciprocate in fa -median position, providing ir'i'stead'fsome dvicefor resetting it vvhlevr'itdiiftsot ofposilti'n i In this'invention as both"'the main cylinder and the piston or pistons reciprocate whichever one is connected to the carriage 13, the pipes 57 and 58 are shown connected to exible conduits such as rubber hoses, fragments of which are shown at 101 and 102.

It will thus be seen that there has been provided by this invention a machine toolicarr'ia'ge reciprocating mechanism in accordance with which the Various objects hereinabovelset 'forth together with lthoroughly 'practical advantages are successfully achieved, As many possible embodiments maybe made of the' above invention and as many changes might 'be madein the'embodiment above set forth, it is to be understood that allvmatter hereinbefore set forth or shqvvn in the accompanying drawings is to`be"interpreted as illustrative and not in a limiting sense.

l claim:

l. Machine tool carriage and reciprocating mechanism comprising `a machine'tool'carriaggA supporting means supporting said carriage for rectilinear'1'ecipro'c`ation, `a large mass, supportingme'ans :supporting I'said large mass forA rectilinear reciprcation parallel to tthe rectilinear reciprocation of said carriage, a'pistoh and cylinder 'apparatus, one 4of Said'carriage andsaid large massbeing connected to the piston of said piston and 'cylinder apparatus and the other of said carriageand said large mass being connected to the cylinderof 'said pistonand cylinder apparatus Whereb'y the reaction due to the reversal of'the rectilinear motionof the carriagefis absorbed by reciprocating said large'r'nass."` i

2.` Machine tool carriage and reciprocating mechanism according to claim l having means exerting opposed forces on said large mass which opposed forcesare increased when the mass is moved against them respectivelyr 'thereby to tend vto'retiir said 'largemass'to a' position'vfhere the two opposing forces 'are substantially equal.`

3. Machine tool carriage 'and reciprocating mechanism accordingt lai'm 2 having dampeningfmeans 'to' dampen the resultant reciprocatiori's o'fsid'lar'ge mass due 'tothe reaction from reversal of the carriage. Machine toolcairiage'andrciprocatiug mechanism according to claim 1 having dampening means toY dampen the resultant reciprocations of1 said large' mass due' tothe reaction from reversal` of the carriage'. i A

No references cited. 

